The proposed studies will focus on the effects of disfluencies on parsing and interpretation processes. The proposed experiments are based on the results of extensive preliminary work demonstrating the viability of the key assumptions. Disfluencies influence the operations of the syntactic parsing mechanisms by causing the parser to be committed longer to the structure it is in the process of building when the disfluencies are encountered. In addition, disfluencies tend to occur before certain types of constituents, and so they provide useful information to help the parser choose from among possible structural alternatives. A particular type of disfluency - corrections - may influence parsing because the misarticulated information is sometimes relevant to choosing between rival syntactic analyses of an ambiguous string. The proposed studies (ten in total, each consisting of 1-3 experiments) will lead to a better understanding of how the fundamental mechanisms of the language processing system accommodate and even take advantage of disfluencies in speech. They will also contribute towards the development of basic models of language processing, because disfluencies can be used as a tool to decide between rival architectures of the comprehension system. This research ultimately may contribute towards the creation of a more ecological approach to psycholinguistic questions - an approach that acknowledges the important role of linguistic structures in processing but pays more attention to the real properties of linguistic stimuli encountered in normal conversational contexts. The research is important for the development of basic models of language processing, but in addition the results would have important implications for studies of how individuals suffering from health-related cognitive disorders understand language, particularly in natural environments.